In the conventional processing of tobacco leaf to form tobacco suitable for the formation of cigarettes, the lamina portion of the leaf first is separated from the stem portion of the leaf by threshing, the lamina portion is cut or shredded to a size suitable for cigarette making, the stem portion usually is flattened and cut, and the resulting cut rolled stem (CRS) is mixed with the cut lamina shreds, or a blend of shreds, for example, by tumbling together in a rotating cylinder, to form the feed mix for the cigarette making machine. Although the cut rolled stem mixes well with the tobacco lamina shreds, the cut rolled stem tends also to separate readily from the tobacco shreds and hence tends not to remain uniformly mixed and distributed within the shreds, to the ultimate detriment of the quality of cigarette which is produced therefrom.
The applicants herein have developed a new procedure for the processing of stem material which involves the shredding of the stem between rotating ribbed plates. The latter procedure is the subject of U.S. Pat. No. 244,083 filed Mar. 16, 1981. (Now U.S. Pat. No. 4,386,617) in the names of Warren A. Brackmann et al and assigned to the assignee hereof, the disclosure of which is incorporated herein by reference. As set forth in this U.S. patent application, tobacco stem material first is thoroughly soaked in water to provide a moisture content of about 30 to about 60 wt %, the soaked stem material then is fiberized between counter-rotating ribbed discs spaced apart from 0.05 to 0.30 inches (1.25 to 7.5 mm), and then the fibrous shredded stem material is dried to a moisture content in the range of about 10 to about 16 wt %.
The product of the latter procedure is quite fibrous in character and has a similar physical appearance and has similar physical properties to the shredded lamina material. The reduced stem material is quite different in this respect from the cut rolled stem material which tends to be much more particulate in form.
Potentially, therefore, the shredded stem material is superior to cut rolled stem as a cigarette filler rod component. However, the fibrous shredded stem material resists ready mixing with the shredded lamina since both the shredded lamina and shredded stem material tend to form aggregations or clumps of particles.
The problem to which the present invention is directed is how to mix together effectively shredded stem material and shredded lamina material, so that the beneficial properties of the shredded stem material may be realized in cigarette making.